Molding apparatus



Jan. 8, 1946. w, A. TAYLOR Momma APPARATUS 2' sheets-sheet 1 Filed Feb.20, 1943 uwwm NKNM.

Jan. 8, 1946, w. A. TAYLGR 2,392,707

MOLDING APPARATUS Filedv Feb. 20, 1945 2 Sheets-Sheet 2 H T TPNE YPatented 8,1941? 1jr unirse srnrss wwf' Muur ortica Momma demeureswilliam A. Taylor, Wildwood, N. J., assigner to Vidal Corporation, acorporation oil Delaware 1 Application February 2li, 1943, Serial No.476,537 3 Claims. (Cl. M15- 281) This invention relates to certain newand useful improvements in iiuid pressure mol apparatus. l

Objects and advantages of the invention will be set forth in parthereinafter and in partwill e structions, arrangements, combinations andimprovements herein shown and described.

The accompanying drawings, referred to herein' and constituting a parthereof, illustrate one em l@ sediment of the invention, and togetherwith the description, serve to explain the principles o the invention.

in the manufacture ci laminated molded artlcles upon a rigid mandrel,the molding presil@ to provide e. mandrel for molding articles by duidsure is :frequently applied to the moldable niaterial through the mediumof a fluid under pressure, such, for exemple, as high pressure steam. orair, acting through a fluid-impervious mera dlmculty of removing fluidtrapped between the mandrel and moldable material as the latter conformsto the mandrel surface. f It is obviously desirable also that themandrel possess high resistance to warping, crushing, y.bending andtwisting. Wooden maudrels are ad vantageous in that their construction ybe carried out with relatively non-skilled labor and for a given sizethey are of lighter weight and cost less to fabricate than mandrels ofconcrete or metal. In large sizes, however, it has been dimcult toimpart to them the necessary strength factors so that they will retaintheir exact form with continuedusage over long periods o1 time.

to provide a new and improved wood mandrel having an extended usefulliie and high resistance to crushing, bending, warping and twisting;

pressure transmitted through a iieidlcle membrane which will minimizethe possibilitg'f of injury to the mandrelv or article consequent uponleakage ci the pressure fluid lutothe space be brano, or membranou'scontainer, wholly or par tween the mandrel and 'the membrane; sind, to

tially enveloping thel mandrel and reciclable ma terial assembledthereon.

In order to obtain the necessary diierential molding pressure throughthe membrane, it is customary to vent or exhaust the membranous 3ocontainer While the molding pressure is being applied. It frequentlyhappens that at the high molding temperatures and Ipressures elmlloyed`steam permeates the container, either through the pores of the membrane,or through openings 35 therein created by rough handling, gradualdeterioration, rupture in use, or other causes. Condensation Within thecontainer follows and Water.' collects therein. When the mandrel isrecessed to receive stringers, the Water may collect in the 40 Stringergrooves, and the stringers wetted with ensuing warping, twisting andother injurious effects.

Success of the molding operation is facilitatedr is desirable to permitpreliminary manipulation of the container on the mandrel. Preliminarymanipulation tends to eliminate factors causing tearing and rupturing ofthe container. Such.

diilculties often arise when the container is per- 60 The slowness isapparently due to the 55 provide a mandrel which will enable said spaceto be evacuated more rapidly than i ashereto fore been possible.

f 0f the drawings: Y

Fig. l is a View in side elevation with parte in section of a fuselagemandrel constituting one embodiment of this invention;

Fig. 2 is a view in elevation of the left end of the mandrel of Fig. 1;

Figs. 3 and 4 are sections resctively taken ,along the lines 3 3 and e-dof Fig. 1;

Fig.I 5 is a view in vertical section through fluid pressure lmoldingapparatus showing the mandrel of Fig. l with moldable material thereon;

Fig. 6 is a view in perspective of the llfth and sixth contoursectionsfrom the left end of the mandrel of Fig. 1;

Fig. 7 is a view in side elevation of a binnacle stand mandrelconstituting another embodiment if the container is first evacuated.Evacuation 46 of this invention; the mandrel being in the po-v sition itwould occupy duringja molding operation; and,

Fig. 8 is a view in end elevation of the left end of the mandrel of Fig.7.

To the accomplishment of the foregoing ends and objects, there isprovided in accordance with this invention, a wooden mandrel comprisinga. strong and rigid assembly of individual units of wood. These unitsare so constructed and arranged that in their assembled relationship,the

Objects of this invention are: to provide improveniente in fluidpressure molding apparatus; f

wood grain of each will run substantially. normal drel from whence itcan be removed by suction through a. non-molding surface of the mandrel.

'Ihe term molding surface as used herein is intended to includeallportions of the mandrel surface with which the moldable material,including any and all reinforcing elements thereof, comes in contact orcovers. Thus, it will be understood that the bottom and side Walls of agroove in the mandrel, adapted to receive a preformed stringer, forexample. may form part of the molding surface. l

I'he term non-molding surface" as used herein refers to a surface notcontacted or covered by moldable material although it may be, andgenerally is contacted, or covered bythe pressure transmitting membrane,sometimes hereinafter referred to as the container, which covers themolding surface of the mandrel during the molding operation.

The same means is also utilized for effecting the withdrawal of air orother gaseous uids from such recesses and from the container whichenvelops the mandrel during the molding operation.

It will also be apparent that through the provision of a drainage systemcommunicating with the space between the molding surface and moldablematerial, the removal of air, as during evacuation of the container,from between the moldable material and the mandrel is facilitated. Inconsequence, evacuation of the container can be carried out inconsiderably less time than is required for the purpose with mandrels ofconventional construction.

In accordance with this invention, the mandrel is built-up of a numberof small wooden members or elements in such fashion as to obtain astructure of .superior resistance to deformation by bending, crushingandtorsional forces. As embodied, these wooden elements are so constructedand arranged that the grain of the wood of the elements forming themolding surface will be normal or substantially normal to the moldingsurface throughout at least the major portion of the molding surfacearea.

Since the direction of action of fluid pressure is normal to the surfaceto which it is applied, the pressure upon the molding surface in a uidpressure molding operation will act in the direction of the wood grain.High crushing resistance is thus obtained so that substantially novariation in the contour of the molding surface will occur even afterextensive use of the mandrel.

In order to facilitate fabrication of the mandrel and at the same timeto impart thereto a greater torsional rigidity, the mandrel comprises anumber of side-by-side contour sections of multiple unit construction.

Each unit of a section is so fashioned that when assembled in itssection its grain will be substantially normal to the molding surface ofits section.

The units of each section are preferably also so fashioned and arrangedthat the seams or juncture lines of any one section will be in angularlyoffset relation to the seams or juncture lines of its preceding and/orsucceeding section. In consequence, increased shear strength isobtained.

Bonding of the successive sections and the units of each section to eachother is obtained by means of a suitable adhesive, preferably a plasticbonding agent, such, for example, as a synthetic resin adhesive of whichDurez, Plaskon and the like scription as well are exemplary andexplanatory but are not restrictive of the invention. Referring now tothe accompanying drawings and more particularly to the embodiment ofFigs. 1 to 6 thereof a fuselage mandrel 9 as there embodied comprises a.plurality of contour sections I0 joined together in side-by-siderelationship by means of dowels Il, inset longitudinal stiffeners I2 andan external longitudinal stiener or spar member I3. It will beunderstood that the mandrel of Fig. 1 is adapted for the fabrication ofone half of a fuselage, two such halves upon completion being assembledinto a unit to form the desired structure.

As will be evident from Fig. 5, material such,' `for example, as laminaeor sheets I4 of wood veneer of which the fuselage is to be constructed,is assembled on the molding surface of the mandrel, layer upon layer, tothe desired thickness. This assembly is then enveloped in a membrane I5of flexible, resilient material such, for example, as rubber, neoprene,etc., forming a bagshaped container or Venvelope I5 through the mediumof which it is possible to subject the assembly to a fluid moldingpressure.

'Ihe container I5 is provided with a removable closure member I6 sealingits mouth and is adapted to be vented and/or exhausted through a venthose I1 which extends through the container I5 in sealing engagementtherewith. One end of the hose I'I is removably lodged in a vent opening3l in a non-molding surface 38 and the other end is `connected -to avalved fitting I8 of a pressure vessel I9. The fitting may be connectedby suitable means to a suction pump (not shown).

The pressure vessel I 9 is equipped with a valved fitting 20 forsupplying fluid under pressure from a suitable source (not shown) to theinterior of the vessel and for releasing' the pressure when the moldingoperation is complete. Suitable devices, such as the pressure gauge 2|,may be provided for determining the operating conditions in the vessel.

It will be apparent that as the container I5 is collapsed, either by thebuilding up of pressure within the vessel I9 or by exhausting the container through the fitting I8, fluid within the container willbedischarged or educted through the tting I8 and the mandrel 9 will besubjected to a uniformly distributed fluid pressure acting normal to theperiphery of the mandrel.

Each of the contour sections I0 is of suitable configuration providing adesired substantially arcuate molding surface over the area which it isdesigned to cover and, as embodied, each is so constructed and arrangedthat the grain of the wood of which it is fashioned is substantiallyradially arranged and substantially normal to its f stlener I3 over theentire contacting area of from a larger unit solas to obtain thisresult.

As embodied in Fig. 6 each unit 23 is of generally epic-shaped"construction so as to 'facilitate and l maire, possible the assembly ofthe units into a.

section of the desired contour with the desired grain arrangement. Theunits 23 of a sectiontare adhesively bonded to each other preferably'bymeans of a synthetic resin adhesive applied to the Vcontacting surfaces.The sections Ill are assembled on the stiifener liii in side-by-siderelationship from right to left as viewed in Fig. l, the severalsections being mechanically bonded together by the dowels Il traversingadjacent sections.

Apertures 25`are provided in eachsection I0 for the reception of thedowels Ii, the apertures being suitably spaced over the sections so thatthe dowels will not be axially aligned lengthwise of `the mandrel.

In the formation oi the sections I0, the units 2S of each section areformed so as not only to obtain the desired grain direction as shown,but also to obtain an angularly offset relationship of the seams orjuncture lines between the units of one section and the seams orjuncture lines of units of a preceding and/or succeeding section. Suchan arrangement is shown in Fig. 6 wherein it will be' noted that thesections depicted, which correspond to the fifth and sixth sections fromthe left in Fig. l., have different numbers of units,

namely, six in the first case and i'lve in the second. A similararrangement of units is preferably followed in the other sections so asto achieve this angularly odset relationship.

The longitudinal stifieners i2, as here embodied fit within grooves 28fashioned in the sections It of the mandrel, Fig. 6. The grooves 26 maybe foed in the mandrel after the sections have been assembled or theymay be formed in the respective units 23 prior to assembly as in Fig. 6.

The stiieners i2 as embodied may be of solid or laminated construction.As here embodied each is a plurality of strips of thinwood veneeraldhesively bonded to the-mandrel in the grooves 26 so as to lie flushwith and conform to the mold ing surface of the mandrel. Each of thethin strips of wood veneer has its grain running lengthwise of the stripso as to provide adequate resistance to twisting and bending ofthemandrei.

The spar stiflener I3 likewise has its grain lrunning lengthwise of themandrel for the same reasons. As here embodied, the stiffener I3 isformed of a number of sideeby-side sections coother as by a tongue andgroove construction 21.

Figs. 2 and 3. Obviously, the stiflener i3 may be a single unit or ofmulti-piece construction employing short elements joined to each otherat their ends and/or at theirl sides. Various mdiiled forms of'stiflener construction will readily suggest themselves to those skilledin the art and such forms are intended to come within the scope of thisinvention. The stiffener I3, as here embodied, forms part of the moldingsurface in that the sides of the stiffener form a continuation of thecontour of the contour sections l0. The latter are preferably adhesivelybonded to the the section I 0 and stlilener I3. l

It will be apparent that the mandrel of Fig. l is oi' a constructionproviding great strength coupled with light weight. It has highresistance to crushing by reason of the arrangement of the grain of thesections lllrnormal to the molding y Means are provided for draining themolding surface 'of the mandrel; for facilitating exhaust lng of thecontainer; and, for preventing the accumulation of liquid aroundremovable string? ers, both transverse and longitudinal, such as areadapted to be contained wholly or partially within recesses in themandrel during molding and to form part of the article being molded.

The venting and drainage means, as embodied, comprise a system of ductsthrough `which fluid is adapted to be conducted by both gravity andsuction from the molding surface, through the mandrel, to a non-moldingsurface oi' the mandrei. v

Referring now more particularly to Fig. l, the mandrel there shown. isprovided with a number of transverse grooves to terminating above thebase of the mandrel. Each of the grooves 30 is adapted to receive apreformed transverse Stringer (not shown) flush with the molding surfaceand ing with the grooves 3u are adapted for the reception oflongitudinal stringers 32, Fig. 5, for a similar purpose. It will beunderstood that it is common inA the art t0 provide such Stringergrooves for the purpose aforesaid and that the number, 'type andarrangement may be suitably varied as may be required. it is to befurther understood, however, that the grooves 30, and thc'grooves BIcommunicating therewith, form part of the drainage system and that byreason thereof liquid will tend to course4 downwardly therein from theupper to the lower reaches of the molding. surface.

Each of the grooves @Il4 is connected at either end by a duct 32 to theopposite ends of one of a number of transverse internal suction ducts'33 in the lower reaches of the mandrel.

The ducts 32, as embodied, may be covered or uncovered so long as theyprovide a. connecting channel between the Stringer grooves 30 and thetransverse internal ducts 33. As here embodied. theducts 32 are in theform of open channels which may be conveniently routed out of thesections I0 during fabrication of the latter and of a. depthcorresponding to thatV of the grooves 33. Obviously, if an open channelin the molding surface be undesirable, the ducts 32 may take the forniof wholly enclosed passageways in the sections Ill. Inv either case,yformation of the channels or ducts is obviously facilitated by thesectional construction of the mandrel.

The transverse ducts 33 form laterally extend- 'I'he vent opening 31, inthe embodiment of Fig.

1, is located at a considerable height above the bottom of the mandrelin order to facilitate attaching the hose I1 to the mandrel.

The header duct 34 is located preferably at a low level in the mandrel,however, to facilitate drainage of liquid by gravity from the upper tothe lower reaches of the mold. The duct 34 is provided with a short highlevel section 36 extending inwardly from the opening 31, the section 36being connected to the low level section of the duct by a riser 35. Y

The duct sections 35 and 36 are preferably drilled in the contoursection I0 during fabrication of the latter. It will be understood that,if l desired, the opening 31 may be located at a lower level in themandrel with the header 34 extend-- ing directly inwardly therefrom.

Referring now to Fig. 5, it will be seen that by applying suction to thefitting I8 air will be exhausted from the container I5 through themandrel via the duct 34 and vent hose I1. Any liquid which collects inthe Stringer grooves 30-3I will drain downwardly by gravity via ducts 32and \be drawn through ducts 33 into duct 34 and from the latter eductedthrough vent hose Il. Duets 39 in the surface of the end wall 38 provideadditional channels through which liquid may course by gravity fromlongitudinal Stringer grooves 3| to opening 31. The vent hose I1 whereit enters the opening. 31 may be provided with apertures into which-suchliquid is drawn and by which direct evacuation of the container may beeffected.

.Thus it will be seen that through the provision of the internaldraining and venting system, accumulation of moisture on the mandrel isminimized, the rigidity and resistance to twisting, warping and swellingprovided by the multiple unit construction will be preserved, themandrel life is prolonged and evacuation of the container isfacilitated.

It is also apparent that in the event a leak occurs in the container I5,a readily condensible pressure fluid, such, for example, as steam whichmay condense on the molding surface will drain by gravity through theduct system from the upper to the lower reaches of the mandrel and beeducted through 'the hose I1 to the outside of vessel I9. In this way,there can be no accumulation of liquid in the bottom of the container I5to be raised by the pressure medium to the top of l the mandrel so as towet stringers, such as the stringers 32, adapted to be contained withinthe grooves and 3 I.

Referring now to the embodiment of the invention shown in Figs. 7 and 8,there is depicted a wooden mandrel |03 of generally cylindrical contoursuch as would be employed in the fabrication of an internally reinforcedhollow laminated cylindrical molded structure such, for example, as albinnacle stand.

As there embodied, the mandrel |09 is provided with longitudinallyextending strin'ger grooves |3| gravity drainage ducts '|32 and aninternal low level header duct |34 having .a high level section |35 andvertical section |38.

The header duct |34 terminates in a high level aperture |31 inend wall|38 but it Will be observed that the gravity drainage ducts 32 leaddirectly to the header duct |34, the latter being located in the lowerreaches of the mandrel.

It will be understood that the term lower reaches of the mandrel is arelative one since it depends on the position of the mandrel in thepressure vessel during molding. Obviously, however, a mandrel embodyinga drainage system in accordance with this invention would be placed inthe pressure vessel so that the drainage system would function in themanner intended. In such case, the terms upper and lower reaches areclearly descriptive and it is believed they will be clearly understoodby those skilled in the art.

Thecontour sections ||0 are of multiple unit construction. Each section,as embodied, is assembled from a number of segmental units |23 ofidentical contour, the stringer grooves |3| being routed in the mandrelpreferably after assembly of the sections I0 into their final structuralrelationship,

'I'he units |23 are so fashioned that the grain of each will besubstantially normal to its melding surface portion |24. -Each sectionis also preferably angularly offset relative to its preceding and/orsucceeding section so that the seams or juncture lines of\successivesections are out of alignment with each other.

Longitudinal stiffness and torsional rigidity is enhanced to the desireddegree through the provision of the short dowels joining successivesections and successive groups of sections so as to provide a firmlyintegrated structure. It will be understood that the dowels I|| havetheir grain running longitudinally of the mandrel, that is, parallel tothe molding surface and at right angles to the grain of the successivesections I0.

It will be apparent that with the mandrel |09, liquid which wouldotherwise tend to accumulate in the upper grooves |3| will draintherefrom through the gravity ducts |32 intoy the header duct |34.Suction applied to the duct |34 via the opening I 31 will educt the uidtherefrom. Educ-- tion of fluid from the container in which the mandrelis-located during molding will be facilitated by the drainage system inthat by reason thereof, the escape of fluid from between the mandrel andmoldable material is made easier.

The invention in its broader aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and Without sacrificing its chiefadvantages.

What is claimed is:

1. A mandrel comprising in combination a series of wooden contoursections in side-by-side relation, each said section comprising aplurality of solid integral wood units substantially radially arrangedin side-by-side relationship, each unit having its wood grain extendingsubstantially radially thereof and substantially normal to a surfacethereof forming a molding surface portion of the mandrel; an externalwooden spar member uniting said sections; and, wooden stiifeners insetin and .f uniting said contour sections, the wood grain of said sparmember and said inset stiifeners running in the same directionsubstantially parallel to the molding surface of said mandrel and y2,392,707 at substanuany right angles to th wood gram of said contoursections.

2. A wooden mandrel comprising a plurality of wooden contour sectionsarranged in side-by-side relation, each said section comprising aplurality of solid integral wood units substantially radially arrangedin side-by-side relationship, each said unit having its wood grainrunning substantially normal to a surface thereof forming armoldingsurface portion of the mandrel, the juncture lines between adjacentunits of a section being angularly offset relative to the juncture linesbetween adjacentv units of an adjacent section; and, wooden stiieningmembers uniting said sections to each other, each said member having itswood grain running substantially at right angles to the wood grain ofsaid unit. J

3. Clin a fluid pressure molding apparatus for the fabrication ofreinforced molded articles, the combination with a pressure vessel and apressure transmitting membrane of a wooden mandrel in said vessel to themolding surface of which a fluid molding pressure is adapted to betransmitted through said membrane,v said mandrel having grooves for thereception of reinforcing elements for said articles and comprising aplurality of wooden contour sections arranged in sideby-side relation.,each section having its wood .A grain running substantially normal to asurface thereof forming a molding surface portion of said mandrel, saidmandrel having additionally a venting and drainage system for theeduction of fiuid from said grooves and areas of the molding sur facecontiguous thereto, said system comprising gravity drainage ductsleading from said grooves 20 said vessel.

f WILLIAM A. TAYLOR.

